As smartphones, tablets, and other portable computerized devices have become more powerful and more commonly used, a wide variety and large number of applications for such devices have become available. Many smartphones and tablet computers often initially include several applications that provide a base set of functions, such as a telephone application, a camera application, a web browser application, and a navigation tool, and are affiliated with or are capable of connecting to one or more application stores or markets that provide a multitude of additional applications.
A user can generally interact with such applications by entering input using a presence-sensitive touchscreen display operatively coupled to or otherwise associated with the device. For example, the device can detect whether a finger is pressing a fixed-image touchscreen button, or can detect the presence and position of a finger at or near the presence-sensitive display, facilitating functions such as dialing a cell phone, navigating using a Global Positioning System (GPS) device, or typing using a virtual keyboard to perform tasks such as composing a message or browsing Internet content. Many applications also use an audio interface, such as a microphone and speaker used for a telephone application, or a speaker used to provide voice instructions, sound effects, or alert sounds.
However, in some situations, users wearing hearing aids may not hear a mobile device's alerts or other sounds, such as a ringing telephone, a calendar reminder tone, or a text message notification, particularly if the mobile device's volume is not set high or if the mobile device is in a pocket or handbag. Noisy environments can make it even more difficult for a hearing aid user to hear alert sounds, and the frequency range of alert sounds often falls outside normal speech frequencies for which many hearing aids are configured. Alert sounds produced by a carried mobile device may therefore go unnoticed, resulting in missed phone calls, missed calendar appointments, and slow response to text or voice messages.